Torque wrench



Sept. 19, M LL TORQUE WRENCH Filed April 23, 1959 INVENTOR.

MARTIN J. GILL ATTORNEYS United States Patent 3,000,209 TORQUE WRENCH Martin I. Gill, Attleboro, Mass., assignor to Apco Mossberg Company, a corporation of Massachusetts Filed Apr. 23, 1959, Ser. No. 808,423 4 Claims. (Cl. 73-139) One of the objects of this invention is to provide a 4 torque wrench in which there will be because of the arrangement of the parts a minimunr amount of backlash in the dial indicating mechanism. 1 v 7 Another object of the invention is to provide an arrangement so that adjustment of the dial indicating reading may be had without disassembling the entire structure.

Another object of the invention is to provide a casing and assemble into the casing the essential operation parts so that these parts may be easily removed for repair when desired.

Another object of the inventionis to provide a work bar which may be assembled with a casing which work bar will carry the reference plate and also the dial indicating movement, the whole being assembled as a unit into the casing for completion of the wrench.

With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawings:

FIGURE 1 is a top plan view of the wrench;

FIGURE 2 is a sectional view through the wrench;

FIGURE 3 is a top plan view of the removable work bar and reference plate unit;

FIGURE 4 is a perspective view of one end of the work bar and the reference plate with the relationship of the dial indicating movement thereto;

FIGURE 5 is a perspective view of the arm attached to the reference plate which actuates the dial movement.

In proceeding with this invention, a casing is provided at one end of which there is a rotatable head with which the work engages, and at the other end there is a handle for manipulating the wrench. This casing is generally hollow and in the casing a work bar is provided which has an opening to extend over and have turning relation with the rotatable head at one end, while at the other end a dial indicating movement is carried, the entire bar being fixed in the casing for movement therewith. This bar carries a reference plate which is secured to the bar near the work engaging head end and is free to move at the opposite end in relation to the work bar which carries 'the dial indicator movement. Thus, by applying torque to the casing, it is transferred to the bar and through the bar to the work engaging head and the displacement of the bar, by reason of the torque applied, is a displacement with relation to the relatively stiffer reference plate so that movement exists between the bar and the reference plate in proportion to the torque. This movement is transmitted to a pointer which is swingable over a dial carried by the casing. The casing is open along one side substantially its full length for reception of this bar in ice . this casing. A cover plate closes the casing and encloses the bar. In this cover plate, there is a porthole opposite an adjustable linkage which is located between the, bar and the plate so that by removing a cover which 1 closes this porthole, adjustment may be had as to the amount of movement which will be transmitted to the dial indicating mechanism by the relative movement between the work bar and the reference plate.

With reference to the drawings 10 designates generally a casing which has a top wall 11 and end wall 12 at one end and an enlarged portion 13 adjacent the other end for the reception of a dial 14 and a pointer 15. A suitable glass cover 16 may extend over the dial. A handle 17 extends from or is a continuation of the end of the casing 1 adjacent the dial or the end opposite that having the end wall 12. This casing is generally a casting and is open on its side opposite the top wall 11. This top wall at the end portion adjacent the wall 12 is provided with a circular socket 18 in which is journaled the round portion 19 of the head member, which has a reduced portion 21' which extends through the casing and is rotatably mounted therein. This head member is of a square exterior construction having sides 20 as may be seen in FIG- URE 1.

A work bar 22, as shown in FIGURES 2, 3 and 4, is of a relatively heavy construction and is provided with an opening 23 at one end which is of the same polygonal shape and substantially the same size as the squared portion 20 of the head so as to fit thereover and be in such relation that relative movement of the head will be transmitted in torque relation to this bar. This bar extends 1 substantially the full length of the casing in the hollowed out portion 24 thereof and has an opening 25 at a point located between the mid length of the bar and the end distant from the opening 23 so as to receive a bolt 26' extending through the casing and the boss portion 27 thereof against which the bar rests. This boss portion is substantially the same extent from the inside top wall 11 of the casing as is the socket forming portion of the casing 18 so that the bar 22 resting on both of these seats is substantially parallel to the top wall 11. By this arrangement any torque applied to the handle 17 of the casing is transmitted to the work bar and through the work bar to the rotatable work engaging head. At the end, which is distant from its engagement with the head, the bar is recessed as at 28 and a plate 29 which carries the dial indicator movement designated generally 30 for mounting on one surface of the bar 22 and the movement is housed within this cut away portion 28. This movement has a main driving shaft 31 which is connected through a gear train to the staff 32 upon which the pointer 15 is mounted. 'Ihis shaft 31 has fixed to it an arm 33 which is slotted as at 34 as seen in FIGURE 4.

A reference plate 35 is secured by rivets and screws as at 36 and 37 to the work bar 22. It is of a relatively thin construction and of hardened steel material so that it will not bend widthwise. It extends along the work bar 22 from a point adjacent the opening 23 to a point overlapping the opening 28 and is cut away as at 38 so as to be clear of the bolt 26. Thus, this reference plate will remain relatively stationary or fixed at its free end 39 while the work bar 22 may bend or be displaced at its recessed end 40. Thus, there will be a relative movement between the end 40 of the work bar and the end 39 of the reference plate.

The reference plate is slotted as at 41 at the end 39 and an extension arm 42 is secured on the face of the reference plate 35 which is contacting the work bar, this arm being located in the slot or cut away portion 28 of the work bar. A tongue 43 on this arm extends into the slot 41, while a headed bolt 44 extends through the slot 41 and through a washer 45 and into a threaded open- Patented Sept. 19, 1961.

ing 46 in the arm so as to bind the arm in a position so as to act as an extension of the reference plate 35. This arm is offset as at 47 so as to extend up over the lever 33 of the dial indicator movement as may be seen in FIGURE 4. A pin 48 is fixed in the arm 42 and e'x= desired for adjusting the actuator which will cause the pointer 15 to move.

By carrying the dial indicator movement 30 on the work engaging bar which is itself displaced a minimum amount of backlash is found to occur in the dial indicator movement.

As win be readily apparent, this bar with the dial indicator movement thereon may be easily positioned in the casing with the opening 25 receiving the bolt 26 and the opening 23 receiving the work head 20. A suitable disengaging connection between the start 32 and the hand 15 may be had. Thus, the work bar with all of the main operating parts may be easily removed from or positioned in the casing as a unit. In order to close the casing, there is provided a cover 50 which may be secured to the casing walls by screws 51 located at suitable intervals around the edge of the casing. A porthole is provided in this cover at 52 at a location opposite the screw 44 so that access to the screw for varying the position of the arm 42 may be had. Aplu'g r porthole cover 53 having resilient walls 54 may be inserted in this porthole 42 so as to close the same and is'pro v'ided with bulging portions 55 acting as shoulders to limit the insertion of the plug and also enabling the plug to be easily removed by placing a screw driver or some such chisel-shaped edge in position to start the plug out of its opening.

I claim: 7 V g j 1 In a torque wrench, a casing having a handle ex tending from one end thereof, a head rotatably mounted in said casing at the other end portion of the casing and,

having a polygonal exterior, a bar having an opening of a size and corresponding polygonal shape to receive said head to transmit torque thereto, means to fix said bar to said casing at a point spaced from said opening so that torque transmitted to said handle will be transmitted to said bar and through said bar to said head, a reference plate extending along said bar and secured to said bar to be in fixed relation thereto at the end thereof adjacent 7 said head and free to move with relation to said bar from said location of fixing tothe end distant from the head, said bar being displaceable at the end distant from said head in proportion to the torque turning load on the head member, a dial indicator movement carried by the bar at said distant end thereof, and linkage connecting the movement to said plate to indicate the relative position of said bar and plate. I Q 7 2. In a torque wrench as in claim 1 wherein said linkage is adjustable, said casing having an open side, a removable wall closing said open side, a porthole in said wall to expose said linkage for adjustment and a removable plug closes said porthole.

3. In a torque wrench, a hollow casing having an open side, a rotatable work engaging head at one end thereof in the hollow of said casing, a work bar positionable in said casing through said open side having means to engage said head in torque turning relation thereto, said casing carrying a dial and pointer and said bar carrying a dial movement detachably engaging said pointer, and

a reference plate carried by said bar and'fixed thereto adjacent the end thereof which engages said head but free to move relative to said bar from said location of fixing to the dial movement carrying end of said bar and linkage between said 'plate and movement for actuation of said pointer.

7 4. In a torque wrench as in claim 3 wherein a cover closes said casing to house the work bar therein and has a porthole afiording access to the dial movement and a plug closes said porthole.

References Cited in the file of this patent UNITED STATES PATENTS 2,074,079 Bahr Mar. 16, 1937 2,159,354 Dunn May 23, 1939 2,367,224 Larson et a1 Jan. 16, 1945 

